It’s really a hectic thing if you need to create all different size icons by yourself. iOS app required different size icons for iPhone, iPod, iPad, Retina display, App Store icon, Spotlight icon. Get more info about it at the iOS Developer Library here. There are some tools and online services which lets you generate these icons easily in a click.
1. iOS App Icon Template: This is a commendable work by Danish designer
Michael Flarup. The App Icon Template through Smart Objects in Photoshop, attempts to automate the process of rendering the various sizes that needs to be bundled with iOS Apps.The idea is to edit the largest size and have the smaller sizes automatically rendered enabling a much quicker workflow when designing icons.
It also emulates the App store and iPhone home screen look and shows how the icons will look at these places. This makes it really easy to figure out how the icon will look and feel when the app becomes live at the app store or on a device.
You’ll also find a selection of ready-made textures that you can build on and easy export actions that spit out the exact files you need to deliver to Apple.
iOS app icon template makes icon designing and generating process really easy. And the best thing is that its free. Lots of thanks to its creator.
2. Make App Icon: It’s a free web app which generates all different size of icons for iOS and Android Apps. You will have to provide it with the designed icon image (best preferred size 1024×1024 pixels. supports jpg, png, psd) and it will automatically resize and optimise your icon designs into all formats needed for iOS and Android app.
It displays how the icon will look on your iPhone or Android phone home screen. But it does not shows the itunes screenshot like the iOS App Icon Template.